Inhibition of [³H]Diazepam and [³H]3‐Carboethoxy‐β‐Carboline Binding by Irazepine: Evidence for Multiple “Domains” of the Benzodiazepine Receptor

Abstract: The binding of [³H]diazepam and [³H]3‐carboethoxy‐β‐carboline was examined in rat brain synaptosomal membranes treated with irazepine, an alkylating benzodiazepine. Under incubation conditions that resulted in a 25–33% reduction in the B_max of [³H]diazepam binding, only modest (<8.5%) reductions in the B_max of [³H]3‐carboethoxy‐β‐carboline were observed. The differential effects of irazepine on the binding of these two compounds may be explained by the presence of multiple areas or “domains” on the benzodiazepine receptor.